A closed circulating water system composite bactericide and preparation method thereof

Abstract

The invention discloses a closed circulating water system composite bactericide and a preparation method thereof. The closed circulating water system composite bactericide comprises the following components in parts by weight: 10 to 20 parts of phenols, 60 to 75 parts of formaldehyde, 1 to 5 parts of alkaline catalysts, and 1 to 8 parts of thiourea and alkylthiourea. The closed circulating water system composite bactericide of the invention contains phenolic groups, aldehyde groups and sulfur elements, effectively kills harmful microorganisms such as algae, fungi, iron bacteria, sulfate bacteria, nitrate bacteria, etc. in circulating water, and has good broad-spectrum bactericidal ability; the bactericide has good water solubility, can be miscible with water, has a large molecular weight, is stable in nature, is not easy to hydrolyze, is not easy to volatilize, has the characteristics of small dosage, long maintenance time of effective concentration of the agent, etc., and the preparation cost is much lower than that of the current bactericide.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment agent production, and in particular to a closed circulating water system composite bactericide and a preparation method thereof. Technical Background

[0002] Since the make-up water of the closed system is soft water or demineralized water, there is no water quality problem in terms of scaling. The main considerations are system corrosion and microbial reproduction. There are many varieties of bacteria and algae in the circulating water, but heterotrophic bacteria grow and reproduce the fastest and in the largest number. It basically represents the number of all bacteria in the water, so heterotrophic bacteria are often used to represent the total number of bacteria in the circulating water. The sterilization experiments of this product are based on the conclusions drawn on the killing of heterotrophic bacteria in water (analyzed according to the HJ 1000-2018 standard method).

[0003] The closed circulating water system has the following characteristics: 1. The system water temperature is between 40 and 60°C, which is most conducive to the reproduction of microorganisms; 2. The leakage of organic process media and some corrosion inhibitors added to the water system will provide rich nutrients for the reproduction of microorganisms; 3. It is easy to develop drug resistance; Due to the above characteristics, microorganisms can easily cause large-scale reproduction under the above conditions, and form microbial films on the pipe walls, causing a series of water quality problems such as decreased water flow, corrosion under the pipe wall, and sludge deposition, thereby affecting the normal operation of the system and even causing production accidents. Therefore, the selection of bactericides for closed circulating water systems is a major issue that cannot be ignored.

[0004] At present, the closed circulating water system bactericides commonly used in the water treatment industry are non-oxidizing bactericides such as isothiazolinone and glutaraldehyde. Although isothiazolinone is a broad-spectrum bactericide, its disadvantages are poor water solubility (it needs to be dissolved in an organic solvent or added with surfactants for emulsification before use), poor thermal stability, low effective content (the effective content of the first-class product is 14% to 15%), high cost, and instability in a high pH environment; isothiazolinone is easy to decompose and become ineffective in the working conditions of high water temperature and high alkalinity (pH8.5 to 10) in a closed system, which affects its bactericidal efficiency. Glutaraldehyde is more likely to polymerize into butanediol aldehyde type unsaturated polymers under alkaline conditions. This polymerization is irreversible. As the number of polymers increases, its activity gradually weakens or disappears, thereby losing its bactericidal effect.

[0005] In actual operation, the two fungicides are used alternately and added once a week to achieve microbial control. 3For the water system, the two agents are added 26 times a year, isothiazolinone is 100mg / L, and glutaraldehyde is 200mg / L. The annual consumption of isothiazolinone is 2.6 tons, and the annual consumption of glutaraldehyde is 5.2 tons. The price of isothiazolinone is 12,000 yuan per ton, and the price of glutaraldehyde is 12,500 yuan per ton. The annual cost of fungicides for this system is 96,200 yuan. The labor cost is 200 yuan per time, and the labor cost is 10,400 yuan. Adding the two together, 1000M 3 The total annual cost of microbial control for the water system is 106,600 yuan.

[0006] The present invention is aimed at the problem of controlling microorganisms in the operation of the above-mentioned closed system, and has developed a composite bactericide for a closed system to improve the safety of the system operation and reduce the system operation cost. Summary of the invention

[0007] The purpose of the present invention is to provide a closed circulating water system composite fungicide and its preparation method, which mainly solves the problems existing in the above-mentioned prior art. The fungicide, because it contains phenolic group, aldehyde group and sulfur element, has good broad-spectrum performance, can well control the closed circulating water system to be in a safe operating state, and reduce the operating cost. The technical solution of the present invention is as follows:

[0008] A closed circulating water system composite bactericide comprises, by weight, 10 to 20 parts of phenols, 60 to 75 parts of formaldehyde, 1 to 5 parts of alkaline catalysts, and 1 to 8 parts of thiourea and alkylthiourea.

[0009] Preferably, the phenols are one or more of phenol, p-methylphenol and hydroquinone.

[0010] Preferably, the catalyst is one or more of sodium hydroxide and potassium hydroxide.

[0011] Preferably, the thiourea and alkylthiourea are thiourea, N-methylthiourea, N,N ， - One or more dimethylthioureas.

[0012] The present invention also discloses a method for preparing a composite bactericide for a closed circulating water system, and the preparation method is as follows:

[0013] 1) Add the measured materials as described above into the reactor and stir at a constant speed;

[0014] 2) Turn on the reactor heating system, heat the material in step 1) to 50-75° C., and keep the temperature for reaction for 3 hours, then take samples to measure the free formaldehyde content. When the free formaldehyde content is 10%-20% (mass fraction), it is qualified. If it is higher than 20%, continue the reaction until it is qualified; 3) After the reaction is completed, turn on the reactor cooling system, reduce the material temperature to room temperature, and store it at 5-10° C. to complete the entire preparation process.

[0015] Preferably, in a method for preparing a composite fungicide for a closed circulating water system, the reaction time is 3 to 6 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The closed circulating water system composite fungicide condenses multiple fungicidal groups on one molecular chain at the same time, so it has a broader spectrum of fungicidal performance, overcoming the defect that a single fungicide is only effective against specific microorganisms. The use of the fungicide of the present invention is equivalent to using multiple fungicides at the same time, which effectively solves the problem of microbial resistance.

[0018] 2. The closed circulating water system composite bactericide is a long-chain polymer that is not easy to volatilize or hydrolyze. It is stable in water and has a long-term bactericidal effect.

[0019] 3. The closed circulating water system composite fungicide has a simple production process, readily available raw materials, low price, easy promotion and high cost performance. DETAILED DESCRIPTION

[0020] Example 1

[0021] A composite bactericide for a closed circulating water system comprises, by weight, 15 parts of phenol, 5 parts of hydroquinone, 72 parts of formaldehyde, 2 parts of sodium hydroxide, 2 parts of potassium hydroxide and 4 parts of thiourea.

[0022] A method for preparing a composite bactericide for a closed circulating water system, the specific steps are as follows:

[0023] (1) Add measured phenol, formaldehyde, sodium hydroxide, and potassium hydroxide into a reaction kettle, start stirring, and add a certain amount of hydroquinone and thiourea;

[0024] (2) Turn on the reactor heating system, heat the material to 50-75°C, and keep the temperature for 3 hours, then take a sample to measure the free formaldehyde content. When the free formaldehyde content is 10%-20% (mass fraction), it is qualified. If it is higher than 20%, continue the reaction until it is qualified;

[0025] (3) After the reaction is completed, the reactor cooling system is turned on to reduce the material temperature to room temperature and store at 5-10°C. The preparation is completed.

[0026] In this embodiment, hydroquinone is added to increase the phenol content. Since the phenol has strong permeability, it can penetrate into the mud, which is more conducive to use in the case of mud in the system, and can quickly remove the mud originally attached to the system. The addition of potassium hydroxide improves the water solubility of the product. The product of this embodiment is generally better for the first addition or when there is mud attached to the system.

[0027] Table 1. Sterilization rate of the product in this example at different temperatures and pH

[0028]

[0029] It can be seen from the experimental data that the product of this embodiment is not sensitive to temperature and pH, and the sterilization rate does not change much in a high temperature and high pH environment, which is very suitable for the operating conditions of the water quality of the closed system.

[0030] Table 2. The sterilization data of the product of this example according to the dosage of 50 mg / L, the experimental temperature of 50°C, the pH value of 9.0, and the sterilization data of the agent over time

[0031]

[0032] As can be seen from the above table, after adding the agent, the number of bacteria reached the lowest value in 32 hours, and then slowly increased. The number of fungi was basically qualified within 7 days, indicating that the product of this embodiment has obvious bactericidal and antibacterial effects.

[0033] Example 2

[0034] A closed circulating water system composite bactericide. According to weight, phenol 8 parts, p-methylphenol 8 parts, formaldehyde 73 parts, potassium hydroxide 3 parts, sodium hydroxide 2 parts, thiourea 3 parts, N-methylthiourea 3 parts.

[0035] The preparation method of the closed circulating water system composite bactericide comprises the following steps:

[0036] (1) Add measured phenol, formaldehyde, and sodium hydroxide into the reactor, start stirring, and add a certain amount of p-methylphenol, thiourea, potassium hydroxide, and N-methylthiourea.

[0037] (2) Turn on the reactor heating system, heat the material to 50-75°C, and keep the temperature for 3 hours, then take a sample to measure the free formaldehyde content. When the free formaldehyde content is 10%-20% (mass fraction), it is qualified. If it is higher than 20%, continue the reaction until it is qualified;

[0038] (3) After the reaction is completed, the reactor cooling system is turned on to reduce the material temperature to room temperature and store it at 5-10°C to complete the entire preparation process.

[0039] In this embodiment, the addition of p-methylphenol and N-methylthiourea can produce more straight-chain molecules and reduce branched molecules in the product. The straight-chain molecules can better disperse the killed fungus residues in the water, reduce the deposition of these residues on the surface of the equipment, and eliminate them from the system through filtration, thereby maintaining better operation of the system.

[0040] Table 3 shows the sterilization rate of the product in this example at different temperatures and pH values.

[0041]

[0042] It can be seen from the experimental data that the product of this embodiment is insensitive to temperature and pH, and has stable properties under high water temperature and high alkalinity.

[0043] Table 4. The sterilization data of the product of this example according to the dosage of 50 mg / L, the experimental temperature of 50°C, the pH value of 9.0, and the sterilization data of the agent over time

[0044]

[0045] As can be seen from the table above, after adding the agent, the number of bacteria reached the lowest value 40 hours later, and then slowly increased, indicating that the agent itself has a relatively long-term bactericidal and antibacterial effect.

[0046] Example 3

[0047] A closed circulating water system composite bactericide, according to weight parts, p-methylphenol 15 parts, formaldehyde 73 parts, sodium hydroxide 2 parts, potassium hydroxide 3 parts, N, N ， - 7 parts of dimethylthiourea.

[0048] The preparation method of the closed circulating water system composite bactericide comprises the following specific steps:

[0049] (1) Add measured formaldehyde, sodium hydroxide, and potassium hydroxide into the reactor, start stirring, and add a certain amount of p-methylphenol, N, N ， - dimethylthiourea;

[0050] (2) Turn on the reactor heating system, heat the material to 50-75°C, and keep the temperature for 3 hours, then take a sample to measure the free formaldehyde content. When the free formaldehyde content is 10%-20% (mass fraction), it is qualified. If it is higher than 20%, continue the reaction until it is qualified;

[0051] (3) After the reaction is completed, the reactor cooling system is turned on to reduce the material temperature to room temperature and store it at 5-10°C to complete the entire preparation process.

[0052] In this embodiment, the product is a straight-chain compound. By controlling the degree of reaction, the molecular weight of the product is within a certain range. The product has better water solubility and can better spread the effective bactericidal groups in water, making it suitable for sterilization and algae removal in daily systems.

[0053] Table 5. Experimental data of the product of this embodiment at different temperatures and pH

[0054]

[0055] It can be seen from the experimental data that the product of this embodiment is insensitive to temperature and pH, has stable properties under high water temperature and high alkalinity, and has good bactericidal ability.

[0056] Table 6. The sterilization data of the product of this example according to the dosage of 50 mg / L, the experimental temperature of 50°C, and the pH value of 9.0 over time

[0057]

[0058] As can be seen from the table above, after adding the agent, the number of bacteria reached the lowest value in 48 hours, and then rose very slowly. Ten days after adding the agent, the number of heterotrophic bacteria slightly exceeded the standard, indicating that the agent has an excellent antibacterial effect and is suitable for daily use.

[0059] The cost of the bactericide of the present invention is 5000 yuan / ton to 6000 yuan / ton according to different formulas. The dosage is generally 50 mg / L and it is added once every 2 weeks. According to a 1000M3 water system, it is added 26 times a year, 50 kg each time, 1.3 tons a year, and the cost of the agent is calculated at 6,000 yuan / ton, the cost of the agent is 7,800 yuan, the labor cost is 200 yuan each time, 5,200 yuan a year, and the annual system sterilization cost is 13,000 yuan, which saves 87.8% of the cost compared with the traditional sterilization scheme.

[0060] Although only three embodiments are listed in the present invention, various raw material ratios can be flexibly adjusted according to the characteristics and needs of different manufacturers, different regions, different industries, and different treatment stages of the closed circulating water system, so as to tailor a suitable fungicide formula for a single water system to achieve the best safety requirements and the best economic benefits.

Claims

1. A method for preparing a composite bactericide for a closed circulating water system, characterized in that: The closed circulating water system composite bactericide comprises, by weight, 15 parts of phenol, 5 parts of hydroquinone, 72 parts of formaldehyde, 2 parts of sodium hydroxide, 2 parts of potassium hydroxide, and 4 parts of thiourea. The specific steps of the preparation method are as follows: (1) Add measured phenol, formaldehyde, sodium hydroxide, and potassium hydroxide into a reaction kettle, start stirring, and add a certain amount of hydroquinone and thiourea; (2) Turn on the reactor heating system, heat the material to 50-75°C, and keep the temperature for 3 hours, then take a sample to measure the free formaldehyde content. When the free formaldehyde mass fraction is 10%-20%, it is qualified. If it is higher than 20%, continue the reaction until it is qualified; (3) After the reaction is completed, the reactor cooling system is turned on to reduce the material temperature to room temperature and store at 5-10°C. The preparation is completed.

2. A method for preparing a composite bactericide for a closed circulating water system, characterized in that: The closed circulating water system composite bactericide comprises, by weight, 8 parts of phenol, 8 parts of p-methylphenol, 73 parts of formaldehyde, 3 parts of potassium hydroxide, 2 parts of sodium hydroxide, 3 parts of thiourea, and 3 parts of N-methylthiourea. The preparation method of the closed circulating water system composite bactericide comprises the following steps: (1) adding measured phenol, formaldehyde and sodium hydroxide into a reaction kettle, starting stirring, and adding quantitative p-methylphenol, thiourea, potassium hydroxide and N-methylthiourea; (2) Turn on the reactor heating system, heat the material to 50-75°C, and keep the temperature for 3 hours, then take a sample to measure the free formaldehyde content. When the free formaldehyde mass fraction is 10%-20%, it is qualified. If it is higher than 20%, continue the reaction until it is qualified; (3) After the reaction is completed, the reactor cooling system is turned on to reduce the material temperature to room temperature and store it at 5-10°C to complete the entire preparation process.

3. A method for preparing a composite bactericide for a closed circulating water system, characterized in that: The closed circulating water system composite bactericide comprises, by weight, 15 parts of p-methylphenol, 73 parts of formaldehyde, 2 parts of sodium hydroxide, 3 parts of potassium hydroxide, N, N ， -7 parts of dimethylthiourea, the preparation method of the closed circulating water system composite bactericide, the specific steps are as follows: (1) Add measured formaldehyde, sodium hydroxide, and potassium hydroxide into the reactor, start stirring, and add a certain amount of p-methylphenol, N, N ， - dimethylthiourea; (2) Turn on the reactor heating system, heat the material to 50-75°C, and keep the temperature for 3 hours, then take a sample to measure the free formaldehyde content. When the free formaldehyde mass fraction is 10%-20%, it is qualified. If it is higher than 20%, continue the reaction until it is qualified; (3) After the reaction is completed, the reactor cooling system is turned on to reduce the material temperature to room temperature and store it at 5-10°C to complete the entire preparation process.

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